Binaural hearing systems delivering two separate acoustic signals, one to each ear of a user, generally provide better performance than monaural systems in which a single acoustic signal is delivered to a single ear, in terms of sound clarity, perceived dynamic range, speech perception and a “natural” sound. Binaural systems can achieve a stereo effect. Further, for users with hearing loss each acoustic signal produced by a binaural system can be uniquely customised to best meet the needs of the ear to which it is being delivered, as typically defined by an audiogram. Additionally, each acoustic signal produced by a binaural system can generally be set at a lower volume than is required for a monaural system, putting less stress on the user's hearing.
FIG. 1 shows a typical binaural system, comprising two hearing aids 102, 104, one on each ear of the user. Stereo hearing aid functionality is achieved by ear level microphones and speakers. In simple form the DSP processing at each ear is independent. For best performance binaural systems should not simply comprise two monaural devices operating independently for each ear. Rather, it is desirable for each acoustic signal produced by a binaural system for one ear to be created by processing which also takes into account factors affecting or derived from the other ear, such processing being referred to herein as “integrated” binaural processing. However, to effect such integrated binaural signal processing requires significantly greater complexity and for example requires substantially continuous collection of signal and environment parameters at both ears, for integrated processing by a single processor which can be mounted in either device, or one such processor in each device.
Devices having a speaker at each ear, but which do not gather microphone information at each ear, also suffer a number of disadvantages. For example, conventional telephony headsets can have speakers at each ear, a boom-mounted or wire-mounted microphone near the user's mouth, cheek, or larynx, and a wired or wireless connection from the headset to a controlling device which can be a mobile telephone, desktop computer, or desktop telephone base. The microphone signal can be analysed by the controlling device to implement a range of signal processing techniques such as noise reduction, however with the microphone distal from the ear such devices can not provide effective hearing aid performance as they provide a mono channel and give no directional cues. Moreover integrated binaural processing can not be effected with only a single microphone. Similarly, audio playback devices such as MP3 players and the like can deliver two separate acoustic signals to the respective ears of the user for example to provide a stereo effect, but these devices do not provide a microphone at or proximal to each ear in order that the acoustic signal for each ear can be produced in a manner which takes into account factors affecting or derived from that ear and from the other ear and thus do not provide integrated binaural signal processing.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.